Restraint system and method for high pressure pipeline

ABSTRACT

Restraints are used to restrain a pipeline having pipe segments coupled together in an end-to-end manner. A first restraint is coupled to first and second pipe segments, which are non-adjacent to one another. A second restraint is coupled to third and fourth non-adjacent pipe segments, wherein the third pipe segment is between the first and second pipe segments. The first and second restraints are coupled together at an overlapping portion.

This application is a divisional of U.S. application Ser. No. 13/686,531filed Nov. 27, 2012, which is incorporated herein by reference.

FIELD OF THE INVENTION

The present invention relates to restraining systems and methods forpipelines and in particular for high pressure pipelines.

BACKGROUND OF THE INVENTION

Many applications require pipelines that are capable of withstandinghigh pressures. An example of such an application is found in oil andgas well drilling. After a well is drilled, completion of the well mayinvolve a procedure known as fracturing or “fracking”. In fracking, afluid is pumped down the well at high pressure in order to increase theporosity of flowability of the oil and gas producing formation.

Fracturing pressures can be very high, as much as 15,000 psi. To get asense of how high this is, compare 15,000 psi pressure with the moretypical 60 to 70 psi found in a typical kitchen water faucet.

By its very nature, oil and gas well drilling is a temporary endeavor.During drilling and completion, a drilling rig is positioned on the wellsite. After completion and the well begins to produce, the drilling rigand other equipment are removed from the well site. This includes thefraccing equipment.

The fracturing equipment includes one or more pumps and a pipearrangement that extends from the pumps to the well. The pumps aremounted on a skid or trailer. The pipe arrangement has lengths of pipeconnected together with fittings or couplings. Just like the otherdrilling rig equipment at the well site, the pipe arrangement istemporary; it is assembled onsite and used to convey high pressurefraccing fluid from the pumps to the well, and then it is disassembledafter use and moved to another well site.

During operation, if the pipe arrangement should fail by leaking orcoming apart, then a dangerous situation rapidly develops, made so bythe thousands of pounds of pressure in the pipe. The pipe moves in areaction to the release of the high pressure fluid. In fact, the pipemoves too rapidly for personnel to react. Nearby personnel can beseverely injured, and equipment damaged, by the moving pipe.

A safety restraint system cart be applied to the pipe arrangement and isdesigned to minimize the movement of a pipe in case of a pipe failure.Prior art safety restraint systems are cumbersome, difficult to installand expensive.

SUMMARY OF THE INVENTION

A pipeline restraint system comprises pipe segments having ends andwhich are coupled together in an end-to-end manner to form the pipeline.Each of the pipe segments have an upstream end and a downstream end. Thepipeline has an upstream end and a downstream end. A first restraint iscoupled to a first pipe segment and coupled to a second pipe segment.The second pipe segment is upstream from the first pipe segment and nonadjacent to the first pipe segment. A second restraint—is coupled to athird pipe segment and coupled to a fourth pipe segment. The third pipesegment is between the first and second pipe segments. The fourth pipesegment is located downstream of the first pipe segment. The first andsecond restraints are coupled to each other.

In accordance with one aspect, the first and second restraints arecoupled to each other at a location adjacent to the coupling of thefirst and second pipe segments.

In accordance with another aspect, the first and second restraints arecoupled to each other by a ring.

In accordance with another aspect, the first restraint is coupled to theupstream end of the first pipe segment and to the downstream end of thesecond pipe segment.

In accordance with another aspect, the second restraint is coupled tothe downstream end of the third pipe segment and to the upstream end ofthe fourth pipe segment.

in accordance with still another aspect, the first restraint is coupledto the first and second pipe segments by looping portions of therestraint around the respective first and second pipe segments andsecuring the respective loop so that the respective loop isself-tightening.

In accordance with another aspect, the respective loop is secured by aring.

In accordance with another aspect, a third restraint is coupled to thethird pipe segment and to an anchor. The third restraint is coupled tothe first restraint.

A method of restraining a pipeline, which pipeline has pipe segments,comprises coupling a first restraint to a first set of non-adjacent pipesegments and a second restraint to a second set of non-adjacent pipesegments. A portion of the first and second restraints overlaps. Theoverlapping portions are coupled together.

In accordance with one aspect, the step of coupling the first and secondrestraints to the first and second sets of non-adjacent pipe segmentsfurther comprises coupling the first and second restraints nearrespective ends of the pipe segments with self-tightening loops aroundthe respective pipe segment.

In accordance with another aspect, the self-tightening loops are securedfrom enlarging.

In accordance with still another aspect, the step of coupling theoverlapping portion of the first and second restraints together furthercomprises the step of coupling the overlapping portions with a ring.

In accordance with another aspect, a third restraint is coupled to afirst set of non-adjacent pipe segments and to an anchor so as tooverlap a portion of the third restraint with the first restraint. Theoverlapping portions of the first and third restraints are coupledtogether.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 is a schematic view of a drilling site for an oil and gas wellwith a pipe arrangement, having the safety restraint system.

FIG. 2 is a schematic view of the pipe arrangement with the safetyrestraint system.

FIG. 3 shows a restraint.

FIG. 4 shows another embodiment of a restraint.

FIG. 5 shows a pipe joint with the safety restraint system.

FIG. 6 shows a pipe joint with the safety restraint system in accordancewith another embodiment.

DESCRIPTION OF THE PREFERRED EMBODIMENT

The safety restraint system and method restrains pipe, and inparticular, is well suited for high pressure pipe, in the event of apipe rupture or leak. When a high pressure pipe ruptures, the escape ofhigh pressure fluid produces a reaction force on the pipe. Withoutrestraint, the pipe moves in a direction opposite to the reaction force.The use of safety restraints greatly minimizes the amount of pipemovement and consequently reduces the risk of injury to personnel anddamage to equipment.

The safety restraint system and method are easy to use both in equippingand restraining a pipe arrangement and also in removing the same duringdisassembly for transport to another site.

In FIG. 1, there is shown a typical example of a pipe arrangement, orpipeline, that benefits from a safety restraint system. FIG. 1 shows awell site 11 having an oil and gas well 13 penetrating into the earth 15from a wellhead 16. Located some distance away from the well isfracturing equipment 17, which fraccing equipment includes pumps. Asupply of fracturing fluid (not shown) is provided to the pumps. Thepumps are connected to the wellhead 16 by way of a pipe arrangement 19.Although the restraint system is described in the context of an oil andgas well, the restraint system can be used on pipe arrangements in otherapplications. For example, other oil and gas applications includeflow-back operations, slick water, nitrogen and other energized fluidpumping operations. The restraint system can be used on applicationsother than oil and gas.

In general, the pipe arrangement 19 has a number of pipe lengths, orsegments, 21 coupled together in end-to-end fashion. The pipe lengthsmay be straight, elbows, curved, etc. Most of the pipe arrangement islocated on the ground 15 or elevated on blocks.

Referring to FIG. 2, the pipe arrangement 19 extends from the fracturingequipment 17 to the wellhead 16. The pipe arrangement has straight pipelengths 21Y and elbow pipe lengths 21Z. The elbow pipe lengths 21Z canbe 90 degrees or some other angle. The elbow pipe lengths can be fixedor of the swivel type. The straight pipe lengths 21Y can be of variouslengths (for example 4-10 feet). The pipe can be, for example, two inchinside diameter and of the 1502 type. The pipe arrangement is designedfor high pressure (e.g. 4000-15,000 psi). The pipe lengths 21 arecoupled together with fittings 23. The fittings can be of the hammerunion coupling type.

The restraint system extends from and between anchors, or fixed pointsalong the length of the pipe arrangement. Thus, the restraint systemextends along, and is coupled to, all of the pipe segments in the pipearrangement. In the embodiment shown in FIG. 1, the anchors are thefracturing equipment 17 and the wellhead 16. The anchors are heavypieces of equipment that require more force to move than can be producedby a failed pipe arrangement. Alternatively, an anchor can be a stake ora post located in the ground or anything sufficiently heavy or fixed soas to remain immobile during a failure of the pipe arrangement.

The restraint system 25 (see FIG. 2) includes restraints 31 and couplers33 or constraints.

The restraints 31 are lengths of line, such as rope. The rope can be 12strand braided rope, which is commercially available. Referring to FIG.3, one form of the restraint 31 is a length of line with an eye 35located on each end. The eyes are formed using splices 37. Another formof restraint 31′ (see FIG. 4) is an endless loop, where the two ends ofthe line are spliced 37 or otherwise coupled together.

Alternative materials can be used to form the restraints 31. Forexample, wire cable can be used. Alternatively, webbing, strappingchain, slings, etc. can be used.

The couplers 33 are rings such as shackles. The shackle of course is agenerally “C” shaped piece with a bolt extending through the ends of the“C” to close off the gap. A nut retains the bolt in place. The shacklesare made of metal and are commercially available. Other connectors canbe used, such as circular rings, D-rings, carabiners, etc.

Installation of the restraint system 25 is remarkably easy. Therestraint system can be installed as the pipe arrangement is assembled.Alternatively, the restraint system can be installed after the pipearrangement has been assembled. The respective pipe lengths 21 areconnected by way of the restraints 31, not to adjacent pipe lengths butto non-adjacent pipe lengths. Thus, in the event of a rupture of thepipe arrangement, the pipe is securely retained.

In the description herein, “upstream” and “downstream” are used, with“upstream” being nearer to the fracturing equipment 17 and “downstream”nearer to the wellhead 16. The flow of fluid in the pipe arrangement isfrom the fraccing equipment to the wellhead. The pipe lengths 21 eachhave an upstream end and a downstream end. (An oil or gas well typicallyhas a return pipeline from the well. If the pressures in the returnpipeline require it, the restraint system can be used on the returnpipeline.)

Referring to FIG. 2, it is useful to refer to the pipe segments as 21A21F. One of the pipe lengths 21C has its upstream end coupled by way ofa first restraint 31A to a non-adjacent upstream length 21A. Inparticular, the first restraint 31A is coupled to the downstream end ofthe upstream pipe length 21A. The downstream end of the pipe length 21Cis coupled by a second restraint 31B to the upstream end of anon-adjacent pipe length 21E, which pipe length 21E is locateddownstream of the pipe length 21C.

The non-adjacent pipe lengths 21A, 21E are at least two pipe lengthsfrom the pipe length 21C that is to be anchored by the first and secondrestraints 31A, 31B. Thus, the first restraint 31A is coupled, not tothe adjacent upstream pipe length 21B, but to the next adjacent upstreampipe length 21A. Likewise the second restraint 31B is coupled, not tothe adjacent downstream pipe length 21D, but to the next adjacentdownstream pipe length 21E.

The restraints 31 are coupled to the pipe lengths 21 by way of chokebitches 35 (see FIG. 5). The choke hitches are positioned by therespective pipe length end. The choke hitches are pulled tight. To keepthe choke hitches from coming loose and possibly moving out of positionaway from a pipe end, couplers 33 are used. In the preferred embodiment,the constraint is a shackle inserted into and around the choke hitch.Other types of constraints can be used such as rope, carabiners, splitrings, etc. The restraint has a coupler 33 where the restraint loopsaround the pipe length, as shown in FIG. 5.

The restraints are attached to the pipe lengths by self-tightening loops(for example, the choke hitches. With a self-tightening loop, if therestraint is pulled away from the pipe end, the loop tightens around thepipe. The use of a coupler 33 prevents the loop from expanding andmoving out of position.

Another way to couple a restraint 31 to a pipe length is shown in FIG.6. An eye 35 of the restraint is wrapped or looped about the pipe, withthe eye being closed by a coupler 33. This version is useful forattaching a restraint to an already installed pipe arrangement.

Instead of coupling the restraints together with a shackle, therestraints could be coupled together by passing one restraint through aloop of the other, which loop is around the pipe The loop retains aself-tightening capability and the restraint does not weaken the loop.

The length of the restraint 31 is somewhat longer than the length of itsreach. For example, if the restraint were to cross over an adjacent pipelength that is 10 feet in length, the restraint could be 12 to 14 feetlong. Too short of a length makes it difficult to install the restraint.Too long provides too much slack in pipe movement in the event of a pipearrangement failure. Longer restraints can be made up from the shorterrestraints using brief (square) knots or shackles.

Referring now to the next downstream pipe length 21D of FIG. 2, thisnext downstream length is restrained by third and fourth restraints 31C,31D. The third restraint 31C is coupled to the upstream end of the pipelength 21D and extends upstream. The third restraint 31C does not coupleto the adjacent pipe length 21C, but to the next upstream pipe length21B. The third restraint 31C is connected to the downstream end of thispipe length 21B. Likewise, the fourth restraint 31D is coupled to thedownstream end of the pipe length 21D and extends downstream to anon-adjacent pipe length 21F, where it is coupled to the upstream end.

The respective restraints 31A-31C, 31C-31B, 31B-31D from adjacent pipesegments cross one another. For example, the restraint 31B coupled tothe downstream end of pipe length 21C crosses the restraint 31C coupledto the upstream end of the adjacent downstream pipe length 21D.

To further restrain the pipe segments, the restraints 31 are coupledtogether where they cross one another. In the preferred embodiment, therestraint are coupled together by couplers such as shackles 33, howeverother couplers, such as rings, carabiners and split rings, can be used.Thus, restraint 31A is coupled or shackled 33 to restraint 31C where thetwo restraints cross over one another, which cross over is adjacent tothe fitting 23C between pipe lengths 21B and 21C. Likewise, restraint31C is coupled or shackled to restraint 31B at their cross over pointand restraint 31B to restraint 31D at their cross over point.

The restraints located at the ends of a pipe arrangement, are coupled toanchor points. For example referring to FIG. 2, if pipe length 21A is atthe end of the pipe arrangement, then its end is coupled to an anchor bya restraint 31F. The restraint of the adjacent pipe length 21B, whichrestraint is 31E, is also coupled to this anchor.

The pipe arrangement may have short segments. This is particularly trueat the well head, where short elbow segments are used. Instead of beingconnected to the next adjacent pipe segment, a restraint may pass overmore than one pipe segments to couple directly to the anchor or toanother pipe segment.

After the restraints have been installed on the pipe arrangement, theyare inspected for proper installation. The preferred embodimentrestraint system is easy to visually check, as the restraints cross overone another in a pattern. This makes recognizing and then properlyinstalling a restraint easy.

If the pipe arrangement fails, say at fitting 23C, then the pipe lengths21C, 21D on either side of the fitting remain close to one another dueto the pipe restraint system. The upstream pipe length 21C isconstrained from moving too far because its downstream end is secured topipe length 21E several lengths away. Likewise the upstream end of pipelength 21D is constrained because its upstream end is secured to theupstream pipe length 21B several lengths away. While pipe lengths 21C,21D do move, the movement is greatly constrained.

The restraint system is easy to disassemble. The couplers 33 are removedand the restraint 31 unlooped from the pipe lengths. The restraintsystem can be reused.

The foregoing disclosure and showings made in the drawings are merelyillustrative of the principles of this invention and are not to beinterpreted in a limiting sense.

1. A pipeline restraint system, comprising: pipe segments having endscoupled together in an end-to-end manner to form the pipeline, each ofthe pipe segments having an upstream end and a downstream end, thepipeline having an upstream end and a downstream end; b) a firstrestraint coupled to a first pipe segment and coupled to a second pipesegment, the second pipe segment being upstream from the first pipesegment and non-adjacent to the first pipe segment; c) a secondrestraint coupled to a third pipe segment and coupled to a fourth pipesegment, the third pipe segment being between the first and second pipesegments, the fourth pipe segment located downstream of the first pipesegment; d) the first and second restraints coupled to each other. 2.The pipeline restraint system of claim 1 wherein the first and secondrestraints are coupled to each other at a location adjacent to thecoupling of the first and second pipe segments.
 3. The pipelinerestraint system of claim 2 wherein the first and second restraints arecoupled to each other by a ring.
 4. The pipeline restraint system ofclaim 1 wherein the first restraint is coupled to the upstream end ofthe first pipe segment and to the downstream end of the second pipesegment.
 5. The pipeline restraint system of claim 4 wherein the secondrestraint is coupled to the downstream end of the third pipe segment andto the upstream end of the fourth pipe segment.
 6. The pipelinerestraint system of claim 1 wherein the first restraint is coupled tothe first and second pipe segments by looping portions of the restraintaround the respective first and second pipe segments and securing therespective loop so that the respective loop is self-tightening.
 7. Thepipeline restraint system of claim 6 wherein the respective loop issecured by a ring.
 8. The pipeline restraint system of claim 1 furthercomprising a third restraint coupled to the third pipe segment and to ananchor, the third restraint coupled to the first restraint. 9.(canceled)
 10. (canceled)
 11. (canceled)
 12. (canceled)
 13. (canceled)